[ RadSafe ] Re:Medical Radiological Technician Oversight

[Michael Bohan]

Hello Arthur and RADSAFER's;

In response to your question, I offer the following response:

1.  Why would an  x-ray technologist want to intentionally overexpose a 
patient to x-rays?  The overwhelming majority of techs. are very 
conscientious about using the least radiation possible to produce a 
good quality diagnostic film.  They have extensive technique charts 
that assist them in choosing the appropriate technical parameters for a 
diagnostic procedure.  If they are using a film based system, an 
overexposure would cause the films to be so dark that they would be of 
little diagnostic use.  This would require a retake of the exam.  In 
addition, hospital based radiology departments have QA programs that 
review non-diagnostic films to constantly improve performance and 
reduce retakes.

2.  If they are using newer Computed Radiography (CR) or Digital 
Radiography (DR) equipment, there are almost no retakes because an 
overexposed image can be adjusted to diagnostic quality by adjusting 
the level and window, image parameters.  However, in a hospital based 
radiography program, the QA programs have a Medical Physicist who 
reviews technique parameters and measures x-ray output levels on at 
least an annual basis,  In addition, in CR and DR, every image records 
information about the exposure parameters so they can be reviewed for 
excessive technique.  Most private x-ray facilities have the same QA 
requirements because of State licensing requirements and insurance 
companies will not reimburse for x-rays unless a QA program comparable 
to a hospital's, can be demonstrated.

3.  Even if an "overexposed" image is taken, the radiation levels used 
in diagnostic radiology are well below the levels necessary to result 
in any "real" significant radiation risks (as opposed to theoretical).

4.  The only exception to this in diagnostic radiology, is in long 
fluoroscopic procedures (which are usually therapeutic in nature), 
where due to the complicated procedures being performed, long exposure 
times may be necessary.  However, in these cases, the x–ray is being 
controlled by a physician, not a technologist.  Interventional 
radiology physicians are well aware of this and have adopted techniques 
to minimize the exposures, to avoid acute radiation effects.  The doses 
sometimes achieved in these procedures may get into the level of long 
term radiation risks, however when you compare the mortality and 
morbidity risks of the alternatives (usually surgery or no therapy at 
all), the risk/benefit ratio is usually on the side of the 
interventional radiological procedure.

Regards,

Mike Bohan, RSO
Yale-New Haven Hospital
Radiological Physics
20 York St. - WWW 204
New Haven, CT 06510
Tele: (203) 688-2950
Fax: (203) 688-8682
Email: mike.bohan at yale.edu

Dear Radsafe Folks,

What mechanisims are in place to prevent Medical Radiological Techs 
from intentionally or unintentionally overexposing their patients to 
X-rays?

Sincerely,
Arthur